PT  - JOURNAL ARTICLE
AU  - D Warburton
AU  - L Parton
AU  - S Buckley
AU  - L Cosico
AU  - T Saluna
TI  - Effects of beta-2 agonist on metabolic regulation in the fetal lamb lung.
DP  - 1987 Aug 01
TA  - Journal of Pharmacology and Experimental Therapeutics
PG  - 389--393
VI  - 242
IP  - 2
4099  - http://jpet.aspetjournals.org/content/242/2/389.short
4100  - http://jpet.aspetjournals.org/content/242/2/389.full
SO  - J Pharmacol Exp Ther1987 Aug 01; 242
AB  - To study the effects of beta-2 agonist on metabolic regulation in fetal lamb lung, ritodrine hydrochloride, a preferential beta-2 agonist, was infused i.v. at a rate of 1.3 +/- 0.4 micrograms/kg/min (mean +/- S.D.) for 24 hr into six twin chronically catheterized fetal lambs starting between 0.86 and 0.91 gestation. Lung glycogen was depleted 56% in the ritodrine-infused twins and glycogen phosphorylase a activity was increased 1.8-fold whereas glycogen synthase activity remained unchanged. Cyclic AMP-dependent protein kinase activity increased 1.7-fold, calcium-calmodulin-dependent protein kinase (phosphorylase kinase) activity increased 1.4-fold and calcium-phospholipid-dependent protein kinase (protein kinase C) activity increased 1.6-fold. In addition, the maximal binding capacity of pulmonary beta receptors decreased 49% in the ritodrine-infused twins. However, lung cyclic AMP content was unchanged after 24 hr of ritodrine infusion. We conclude that beta-2 agonist activates protein kinases, depletes glycogen and reduces the binding capacity of beta receptors in the fetal lamb lung. We speculate that these adrenergic mechanisms are involved in regulating the effects of beta-2 agonist on fetal lung liquid and surfactant production.